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Age-dependent changes in the postnatal intestinal microcirculation.
C A Nankervis1, K M Reber, P T Nowicki
1Children's Research Institute Children's Hospital and Department of Pediatrics, The Ohio State University College of Medicine and Public Health, Columbus, OH 43205, USA. nankervisc@pediatrics.ohio-state.edu
Microcirculation (New York, N.Y. : 1994)
|January 10, 2002
Summary
Newborn intestinal blood flow regulation shifts from active control by nitric oxide and endothelin to passive mechanisms within the first postnatal month. This transition is crucial for nutrient absorption after birth.
Area of Science:
- Physiology
- Developmental Biology
- Vascular Biology
Background:
- Intestinal hemodynamics undergo significant changes from fetal to newborn life and during the first postnatal month.
- Basal vascular resistance decreases after birth, further drops by day 3, and then slowly increases by day 30.
- Intestinal blood flow changes inversely with vascular resistance.
Purpose of the Study:
- To describe the circulatory physiology of the perinatal and newborn intestine.
- To emphasize changes in the intestinal microcirculation during early life.
- To discuss age-dependent alterations in intestinal circulation from perinatal to newborn stages.
Main Methods:
- Comparison of terminal mesenteric artery diameter in newborn (1-day-old) versus older (35-day-old) swine.
- Assessment of intrinsic vascular control systems including nitric oxide, endothelin, and myogenic response.
- Evaluation of vascular diameter changes following blockade of nitric oxide or endothelin receptors and pressure/flow perturbations.
Main Results:
- In 1-day-old swine, mesenteric artery diameter is regulated by nitric oxide, endothelin, and myogenic response.
- In 35-day-old swine, mesenteric arteries become passive, showing minimal diameter changes to interventions.
- Postnatal changes in vascular resistance are largely mediated by increased nitric oxide production.
Conclusions:
- The intestinal microcirculation in newborns is actively controlled, unlike in older subjects.
- This active regulation is essential for adapting intestinal blood flow for nutrition post-birth.
- Significant developmental changes occur in intestinal hemodynamic control during the first postnatal month.